Someone once posted here that the closing bars are precision/forgiveness related. As the bars get closer together you get better precision but less forgiveness. If you're confident of hitting the ding, waiting until they get really close to each other will give you a better chance of making a good shot, as long as you got the distance and line right of course. However, if you then miss the ding the deviation will be greater.
I honestly don't know if that is the correct answer but it sounds reasonable.